New bone-like tissue formation in calcific tendinopathy: A case report.

Currently, the pathogenesis of nontraumatic heterotopic ossification (HO), e.g., bone-like tissue in calcific tendinopathy remains unclear. Here, we report a 75-year-old, right-handed Japanese woman who had been on hemodialysis for 3 years and was admitted to our hospital to evaluate pain and swelling of the right forearm. She worked as a cook, and her main job over the 3 most recent years had been the frequent and continuous shredding of cabbage. A radiograph showed the highly radiopaque material on the dorsal aspect of the right wrist and in the right shoulder. The biopsy of this radiopaque material revealed HO with marrow, as well as calcified material. Histomorphometric analysis of the HO identified a severe type of osteitis fibrosa with a fibrous tissue volume to total volume of 19.8% (>0.5% required for diagnosis) and an osteoid volume to bone volume of 20.0% (>15% required for diagnosis). We found more woven bone-like tissue than lamellar bone-like tissue. However, the intact parathyroid hormone level was 3-times the normal upper limit with 203 pg/mL, but histomorphometric analysis of the right iliac crest revealed normal bone structure. These findings indicate that the frequent and continuous shredding action with the right hand contributed to the nontraumatic HO localized on the dorsal aspect of the right wrist.